<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script>
			//alert(String.constructor);
			var str='We change lives';
			var s2=str.toUpperCase(); 
			alert(s2);
			//ange 
			var s4=str.substr(5,4);//从0开始
			alert(s4);
			//ang
			var s5=str.substring(5,8);
			alert(s5);
			
		</script>
	</head>
	<body>
	</body>
</html>
